In such assemblies it is normal for a blade carrying member to be provided with a plurality of slots, normally axial or having some axial extent, within each of which there extends the root portion of one of the blades, the engagement between the root and the slot retaining the blade against radial movement. It is necessary to provide some means for preventing the blade root moving longitudinally in the slot, and one way of carrying this out is to provide lock members which engage both with the blade carrying member and with the blade. The engagement between the lock members and the blade carrying member and/or the blade conveniently comprises a projecting undercut portion of the member or blade which traps the edge of the plate, but it has been found that vibration of the plate can cause fretting between the plate edge and the projecting portion, which in extreme cases may cause the projecting portion to be worn completely away and to free the lock member.
The present invention provides a construction in which the lock member may in operation be clamped more rigidly in place.